The present invention relates to machining systems and, more particularly, to machining systems for the manufacture of machined parts in which a high degree of flexibility and adaptability is maintained while minimizing the time and costs associated with tooling changeover and set-up.
Systems for the manufacture of machined parts have historically been developed as a function of the volume of parts to be produced. Where a large quantity of parts are to be manufactured in a continuous or near continuous manner, as occurs in the automotive industry, specialized machinery is developed for the machining and shaping of a particular part. In general, the development and capital equipment costs for such specialized machine systems is very high although the initial costs can be amortized over the large volume of parts produced to result in lower overall piece-part costs when compared to other types of machining systems. While systems of this type are well-suited for large volume runs, their specialized design is such that they have a low adaptability for the manufacture of parts outside of their design specifications. Where machined parts are required in moderate volumes, as contrasted to high volumes, the design costs associated with dedicated or specially designed machine systems are prohibitive.
Various types of so-called flexible machining systems have been developed to meet the requirements for the moderate volume manufacture of machined parts. In these systems, one or two controllable tool-accepting spindles are made available for receiving various types of edged cutting or shaping bits. The spindles are controlled by a stored-program sequencer or computer that is programed to cause the tools to advance toward and retract from a workpiece, which may likewise be mounted for movement relative to the cutting or shaping tools. In the more sophisticated of these machines, the tools carried by the spindle or spindles are removed and replaced by automatic tool changers. While general purpose flexible machining systems can be adapted to manufacture different types of parts and do not require the substantial capital investment or specially designed systems, it is oftentimes difficult to produce a finished part of moderate complexity on a single stand-alone machine thus requiring additional machines and the transfer of semi-finished parts from one machine to the other. In addition, the operating cycle can be comparatively long for complex parts, oftentimes from six to eight times longer relative to the operating cycle provided by specially designed, high-volume machines. Also, flexible machining systems can require substantial changeover and set-up time to change tooling designed for the manufacture of a first part to tooling designed for the manufacture of another part. While flexible machine systems offer adaptability at reasonable capital costs, their relatively long operating cycles and tooling changeover and set-up times lower the ultimate productivity of the system to thus increase the piece-part machining costs.